Often in display devices, it is useful to incorporate electronic components onto a glass substrate used in the display device. This is especially the case in flat panel display (FPD) devices such as liquid crystal displays (LCD's). In LCD devices, a layer of liquid crystal material is modulated by voltages, which are controlled using electronic components including transistor arrays. Typically, the transistors of the arrays are thin-film transistors (TFT), and are metal oxide semiconductor (MOS) devices.
The LCD displays often comprise a glass substrate with the transistors disposed over the glass substrate and beneath a layer of LC material. The transistors are arranged in a patterned array, and are driven by peripheral circuitry to provide desired switching voltages to orient the molecules of the LC material in the desired manner. Moreover, the transistors of the array are often formed directly on or over the glass substrate from a semiconductor material.
Because the mobility of carriers of a semiconductor is generally greater in crystalline and polycrystalline materials compared to amorphous materials, it is beneficial to grow crystalline structures on or over the glass substrate of the LCD display and fabricating the transistors therefrom. However, for reasons of uniformity and smoothness, the semiconductor films are typically deposited in an amorphous state and then converted to a polycrystalline structure. Typically, these crystalline structures are polycrystalline structures.
Known methods of semiconductor crystalline growth often require annealing a layer of amorphous semiconductor materials at relatively high temperatures or for long time periods. Because the annealing temperatures for crystal growth are too great for the substrate over which the semiconductor crystals are formed, or to speed manufacturing time, other techniques have been explored to meet this desired end. These techniques include laser annealing.
While various techniques have been attempted to form polycrystalline silicon on glass substrates, there are deficiencies in both the resultant material's characteristics and from the perspective of economic feasibility. As such, what is needed is a method of fabricating semiconductor materials over substrates and the structures formed thereby that overcomes at least the deficiencies of the known techniques.